556 F. BASCOM 
marine sedimentation of the period took place, mainly at least, 
beyond the continental shelf. Gravel, which has been included 
in the ‘‘Brandywine” (Early and Late Brandywine), but which 
lies at all places at a lower level than the Early Brandywine gravel, 
is thought to be a terrestrial deposit of Pleistocene streams. Such 
gravel is found on the Chester quadrangle at an altitude of 300 
feet and on Elk Neck, Elkton quadrangle, between 200 and 300 
feet. 
The records of this period of erosion are the dissection of the 
Early Brandywine peneplain, producing the stream terraces and 
Harrisburg 
' Earl : 
oe Brandywine ate Brandywine 
250' i 
rol Norristown quadrangle 
Fic. 20.—Section in Norristown quadrangle 
1000! Chester Quadrangle 
Early Brandywine 
25 Late Brandywine 
Sunderland 
Wicomico Talbot 
Fic. 21.—Section in Chester quadrangle 
the slopes which separate the Early Brandywine peneplain and the 
Sunderland terrace, and the submerged valleys on the continental 
shelf. Late Brandywine slopes are well defined on the Chester 
.quadrangle, and furnish a commanding site for the buildings of 
Swarthmore College. 
The Sunderland, Wicomico, and Talbot terraces have been 
recognized and defined in Maryland.t In Pennsylvania a scarp 
separates the Late Brandywine and the Sunderland. This scarp, 
which the central building of Swarthmore College fronts, represents 
either the old estuarine shore cliff or the escarpment of the wide 
meander belt of Delaware River. 
Erosion truncated the Late Brandywine slopes and dissected 
them and the Early Brandywine peneplain along drainage ways. 
What has been called the Somerville peneplain seems to the writer 
¥ Maryland Geol. Survey, Vol. VI (1906), pp. 61-67. 
